8 COLEOPTERA OP NORTH AMERICA. 



stout with the terminal joint longer, the palpi long and slender, 

 the last joint securiform and concave. Mentum deeply emargi- 

 nate without tooth. Thorax variable in form with a lateral and 

 antebasal setigerous puncture. Body not pedunculate, scutellum 

 scarcely evident. Elytra not margined at base, sides rather 

 widely inflexed, margin acute and not interrupted. Prosternum 

 usually not prolonged behind the coxoe, the tip obtuse, the coxal 

 cavities open behind. Mesosternuni nearly vertical and obtusely 

 carinate in front. Metasternal epimera not distinct. Posterior 

 • coxse separated by a triangular process of the abdomen. Legs 

 long, usually slender, the femora usually very feebly clavate. 

 Anterior tibiae very slightly broader to apex, grooved within 

 near the apex, the spurs terminal but placed slightly obliquely 

 to each other. Tarsi slender, the first joint long, the fourth 

 entire; anterior tarsi usually dilated in the males with a variable 

 number of joints spongy pubescent beneath. 



The separation of the posterior coxae which seems to have 

 escaped notice here as well as in several of the following trilies 

 is a character of too great importance to neglect. It is repeated 

 in Metrius, Promecoguathus, and UnceladiLs, but there exists too 

 wide an interval between the Cychrini and these genera for us to 

 suggest any special affinity with either of them. With the Cara- 

 bini the Cychrini appear to have the closest relationship. 



Two genera form this tribe, both represented in the United 

 States, and the second peculiar to the Atlantic slope. 

 Antennae with four basal joints glabrous. Cychrus. 



Antennae with two basal joints glabrous. Nomaretus. 



Cychrus as above defined is rather polymorphic and is capable 

 of division into parts which rank rather as sub-genera than 

 genera. Those occurring in our fauna have been the subject of 

 a study by Dr. Horn in which these divisions have been treated 

 in sufficient detail (Trans. Amer. Ent. Soc. 1878, pp. 168-185). 



Two important divisions may however be noticed, those in 

 which the anterior tarsi are similar in the sexes and slender, and 

 those with the anterior tarsi dilated in the males. To the first 

 of these series belong some European species and three in our own 

 fauna which occur west of the Rocky Mountains. Those with 

 dilated tarsi are peculiar to our fauna. These two series seem 



